Be careful: this is only accurate if you amend the statement to "smoking weed is bad for you."

According to the Relman Report (the only FDA-sanctioned study done on marijuana effects), the tar content of pot is vastly higher than that of tobacco: they estimated 3 joints to be equivalent to 100 unfiltered cigarettes in this regard.

The lung-damage caused by the smoking of all that tar is the only negative effect ever scientifically-attributed to pot consumption. There have never been any demonstrated long-term negative effects through baked goods or steam inhalation through the use of a vaporiser.